Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
  • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
  • C08J3/05—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media from solid polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/02—Emulsion paints including aerosols
  • C09D5/024—Emulsion paints including aerosols characterised by the additives
  • C09D5/027—Dispersing agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/45—Anti-settling agents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2429/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
  • C08J2429/02—Homopolymers or copolymers of unsaturated alcohols
  • C08J2429/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

Definitions

• the present invention relates to a process for preparing stable aqueous epoxy resin dispersions with finely divided or granulare polyvinyl alcohol (PVOH) as a primary dispersant, and stable aqueous epoxy resin dispersions made thereof.
• the process is a solvent free, and continuous extruder-based dispersion process.
• Stable aqueous epoxy resin dispersions have received growing demand in the coating industry because of their combined ability to coalesce, low volatile organic compound (VOC) content, and low viscosity.
• aqueous dispersions of epoxy resins have been produced by processes wherein epoxy is dissolved in solvent first and then dispersed by conventional dispersant at ambient temperature, and finally solvent is stripped from the dispersion, or by processes wherein at elevated temperatures a molten epoxy resin and an aqueous medium, and a dispersant are mixed by applying shearing force, such as batch dispersion process through phase inversion.
• aqueous polyvinyl alcohol (PVOH) solutions were prepared and used to disperse liquid and high Mw solid epoxy resins in either a batch or continuous process without using a solvent.
• US 4,123,403 to Warner et al. discloses aqueous polymer microsuspensions having controlled particle size and a narrow particle size distribution as prepared by a continuous extruder dispersion process.
• concentrated PVOH solutions were prepared and used as a dispersant to disperse solid epoxy in water in both batch and continuous processes. Nevertheless, in that process, there are several disadvantages. Because the dissolution of semi-crystalline PVOH in water was very slow, taking several hours at 80 deg. C, high contents of PVOH solids, in solution, could not be achieved in a solvent-free processes and the amount water used in the final dispersion could not be controlled. Further, the PVOH foamed after dissolution, and it takes several days for the solution to defoam.
• the present inventors have sought to solve the problem of providing efficient methods for making aqueous epoxy resin dispersions having a controlled mean particle size for coating applications, such as those having average particle sizes smaller than 1 micrometer.
• the present invention provides solvent-free dispersion processes for preparing a stable aqueous epoxy resin dispersion comprising the steps of: i) providing an epoxy resin composition comprising an epoxy resin with an epoxide equivalent weight (EEW) of from 200 to 10000 g/eq, or, preferably, 300 g/eq or higher, or, more preferably, 450 g/eq or higher, and a molecular weight of from 1500 to 40000 g/mol, preferably, 3000 or more; ii) combining the epoxy resin composition with a finely divided or granular dispersant composition comprising a semi-crystalline polyvinyl alcohol in an amount of at least 5.0 wt.% and up to 20 wt.% based on the total weight of the epoxy resin and polyvinyl alcohol, preferably, at least 7 wt.%, or, more preferably, from 7 to 15 wt.%; iii) mixing water with the epoxy resin and dispersant composition; iv) continuously emul
• the processes may further comprise vi) providing additional water; vii) contacting said high internal phase emulsion with said additional water; viii) thereby producing the aqueous epoxy resin dispersion.
• the first epoxy resin, semi-crystalline polyvinyl alcohol can be co-fed into a melt blend zone before the supplying of water.
• the epoxy resin composition further comprises from 0.1 wt.% to 50 wt.% based on the total weight of the epoxy resin composition, a second epoxy resin with an epoxide equivalent weight (EEW) of from 100 to 300 g/eq, and a molecular weight of from 200 to 300.
• EW epoxide equivalent weight
• the molecular weight of the finely divided semi-crystalline PVOH is from 10 kg/mol to 200 kg/mol.
• the average particle size of the semi-crystalline PVOH is from 0.1 mm to 5 mm.
• the dispersant composition further comprises a co-dispersant chosen from a sulfate of an ethoxylated phenol, or a nonionic dispersant having a molecular weight of from 7,000 to 20,000.
• the present invention further provides a stable aqueous epoxy resin dispersion made thereof, and preferably the dispersion has an average particle size of less than 1 ⁇ .
• the molecular weight refers to a weight average molecular weight as determined by gel permeation chromatography (GPC) combined with static light scattering (absolute method) based on polystyrene standards.
• epoxide equivalent weight refers to the value determined by ASTM D-1 652 (1997) (ASTM International, West Conshohocken, PA).
• the phrase "average particle size” refers to a volumetric particle size equal to the diameter of the sphere that has same volume as a given particle.
• the particle size distribution may be measured using a Coulter LS 1 3 320 particle size analyzer (Beckman Coulter, Brea, California) per manufacturer's recommended Procedures via laser scattering. The scattering light from particles through laser scattering and polarization intensity differential scattering is collected as a function of angle, and subsequently converted to a particle size distribution.
• the preparation of the stable aqueous epoxy resin dispersion of the present invention comprises conventional mechanical dispersion of an epoxy resin, a dispersant, a semi-crystalline and partially hydrolyzed polyvinyl alcohol (PVOH), in the presence of water.
• Suitable mechanical dispersion methods may include shearing and, if desired, heating the epoxy resin and the dispersant, with a small amount of water, above the melting temperature (Tm) of the epoxy resin, and the semi-crystalline polyvinyl alcohol (PVOH) or at a temperature that with shearing will heat the epoxy resin, and the semi-crystalline polyvinyl alcohol to melt, to make an aqueous epoxy resin dispersion and, if needed, diluting the aqueous epoxy resin with water while shearing the resulting mixture to form an aqueous epoxy resin dispersion, having a average particle size of less than 1 ⁇ .
• epoxy resin dispersions with average particle size less than 0.5 micrometer can be easily prepared, which is not that easy for prior processes.
• epoxy resin dispersions with different, larger average particle size can also be prepared, for example, average particle size from 0.5 to 1 ⁇ , from 1 to 5 ⁇ , etc.
• Suitable shearing methods include extrusion and melt kneading in a known manner including, for example, in a kneader, a Banbury mixer, single-screw extruder, or a multi-screw extruder.
• the melt kneading may be conducted under the conditions which are typically used for melt kneading an epoxy resin and a semi- crystalline PVOH.
• a preferred melt-kneading machine is, for example, a multi screw extruder having two or more screws, to which a kneading block can be added at any position of the screws.
• an extruder may be provided with a first material- supplying inlet, such as for adding water or liquid epoxy resin, a second material- supplying inlet, such as for the semi-crystalline PVOH, and solid epoxy resin and further third and forth material-supplying inlets in this order from the upstream to the downstream along the flow direction of a material to be kneaded. Further, a vacuum vent may be added.
• the dispersion is first diluted to contain about 10 to about 20% by weight of water and then subsequently further diluted to comprise greater than 25% by weight of water. The further dilution may provide a dispersion with at least about 30% by weight of water.
• Exemplary methods for preparing stable aqueous epoxy resin dispersions are also disclosed in, for example, U.S. Patent Nos. 3,360,599, 3,50391 7, 4,123,403, 5,037,864, 5,539,021 , and WO 2005085331 A. Melt kneading methods are disclosed, for example, in U.S. Pat. Nos. 5,756,659 and 6,455,636.
• the processes of the present invention may include up to 10 wt.%, based on the total weight of the epoxy resin dispersions of an organic solvent or fugitive plasticizer.
• the stable aqueous epoxy resin dispersions are formed in the absence of any organic solvent, which means less than 1 000 ppm or, preferably, less than 500 ppm of solvent.%, based on the total weight of the epoxy resin dispersions.
• a first epoxy resin (a solid epoxy resin in the present invention), and a semi-crystalline PVOH are supplied to the feed throat of the extruder via a loss-in-weight feeder, such as Schenck Mechatron feeder and then melt blended.
• Initial aqueous stream (IA) is then injected into the extruder after the melt blend zone and melt blended epoxy resin is then emulsified in the presence of IA, and thereby produces a high internal phase emulsion (HIPE).
• a second epoxy resin (a liquid epoxy resin in the present invention) stream may be injected into the melt blend zone to melt blend with the first epoxy resin and the semi-crystalline PVOH before entering the emulsification zone.
• a co-dispersant solution may be delivered with the initial aqueous stream (IA) through injector into the extruder.
• the emulsion phase was then conveyed forward to the dilution and cooling zone of the extruder where additional water was added to form the aqueous epoxy resin dispersions having solid level contents in the range of from less than 70 weight percent.
• the initial aqueous stream, the dilution water, co-dispersant solution, and second epoxy resin were all supplied by high pressure positive displacement pumps, such as, an Isco dual syringe pumps (500 ml), or a Gear pump of Zenith Pumps Division, Parker Hannifin Corporation.
• the co-dispersant is finely divided it is fed into the extruder together with the semi- crystalline PVOH.
• the one or more of the epoxy resins and the semi-crystalline PVOH may in molten form be fed into a first mixing device, such as a rotor stator mixer, and brought into contact with water, and optionally a co-dispersant, thereby forming a high internal phase emulsion. Subsequently, the high internal phase emulsion is contact with additional water, thereby producing the epoxy dispersion of the present invention.
• the one or more said epoxy resins may be melted via, for example, a melt pump.
• the first and the second epoxy resin for use herein is a polyglycidyl ether of a polyhydroxy compound, such as a monomeric polyhydroxy compound e.g. a polyhydroxy hydrocarbon, or a hydroxyl- functional oligomer.
• a polyhydroxy compound such as a monomeric polyhydroxy compound e.g. a polyhydroxy hydrocarbon, or a hydroxyl- functional oligomer.
• the polyglycidyl ether is an oligomeric or polymeric compound having at least 2 hydroxyl groups.
• the epoxy resin is the reaction product of a polyhydroxy compound, such as a monomeric polyhydroxy compound e.g. a polyhydroxy hydrocarbon, or a hydroxyl-functional oligomer, with an epihalohydrin, such as epichlorohydrin.
• the polyhydroxy hydrocarbon can be substituted, if desired, with one or more non-interfering substituents, such as halogen atoms, ether radicals, lower alkyls and the like.
• non-interfering substituents such as halogen atoms, ether radicals, lower alkyls and the like.
• polyhydroxy hydrocarbons include polyhydric phenols and polyhydric alcohols.
• monomeric polyhydroxy compounds are resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1 , 1 -bis(4-hydroxylphenyl)-1 - phenyl ethane), bisphenol F, bisphenol K, tetrabromobisphenol A, tetra- methylbiphenol, tetramethyl-tetrabromobiphenol, tetramethyltribromobiphenol, tetrachlorobisphenol A, 4,4'- sulfonyldiphenol, 4,4- oxydiphenol, 4,4'- dihydroxybenzophenone, 9,9'- bis(4-hydroxyphenyl)fluorine, 4,4'-dihydroxybiphenyl, and 4, 4'-dihydroxy-a-methylstilbene.
• hydroxyl-functional oligomers examples include phenol-formaldehyde novolak resins, alkyl substituted phenol-formaldehyde resins, phenol-hydroxybenzaldehyde resins, cresol-hydroxybenzaldehyde resins, dicyclopentadiene-phenol resins, and dicyclopentadiene-substituted phenol resins.
• the polyglycidyl ethers can be prepared by reacting an epihalohydrin, preferably epichlorohydrin, with the polyhydroxy compound including a halogenated
• the polyhydroxy compound used to prepare the epoxy resin is a polyhydroxy hydrocarbon, preferably an aromatic dihydroxy compound, such as bisphenol A and/or bisphenol F.
• An oligomeric or polymeric compound such as a phenol-formaldehyde novolac may be used as the polyhydroxy compound.
• Preferred examples of epoxy resins for use in the present invention include the diglycidyl ether of bisphenol A which is an oligomer of diglycidylether of bisphenol A, typically the reaction product of epichlorohydrin and bisphenol A; the diglycidyl ether of bisphenol F which is an oligomer of diglycidyl ether of bisphenol F, typically the reaction product of epichlorohydrin and bisphenol F; a mixed diglycidyl ether of bisphenol A and F, which is an oligomer of diglycidyl ether of bisphenol A and F, typically the reaction product of epichlorohydrin and a mixture of bisphenol A and F; the diglycidyl ether of a phenol-formaldehyde novolak which is an oligomer or polymer of diglycidyl ether of a phenol-formaldehyde novolak, typically the reaction product of epichlorohydrin and a phenol-formaldehyde novolak;
• thermosettable epoxy resin is a linear, non-cross-linked polymer of bisphenol A and epichlorohydrin having terminal epoxide groups.
• D.E.R. TM 664U solid epoxy resin has medium molecular weight, and is the solid reaction product of epichlorohydrin and bisphenol A, having a softening point of 100 °C to 1 10°C, (The Dow Chemical Company, Midland, Ml).
• the first epoxy resin (solid epoxy resin) of the present invention has an epoxide equivalent weight within the range of from 200 to 10000 g/eq, or, preferably, from 450 to 7500 g/eq, or, more preferably, from 750 to 5000 g/eq; and its molecular weight is within the range of from 1500 to 40000, more preferably, from 2000 to 20000, and most preferably, from 3000 to 1 5000.
• the epoxy resin composition of the present invention comprises a second epoxy resin.
• the second epoxy resin is commonly understood as a liquid epoxy resin, and is from 0.1 wt.% to 50 wt.%, preferably, from 5 wt.% to 45 wt.%, and most preferably from 10 wt.% to 40 wt.% based on the total weight of the epoxy resin composition.
• the second epoxy resin has an epoxide equivalent weight of from 100 g/eg to 300 g/eg, more preferably, from 150 g/eg to 200 g/eg, and a molecular weight of from 200 to 600, more preferably, from 300 to 400, may be further employed.
• the epoxide equivalent weight is determined according to ASTM D 1652 (1997), and the molecular weight is determined according to gel-permeation chromatography (GPC) using polystyrene standard.
• the dispersant may include a finely divided semi-crystalline polyvinyl alcohol (PVOH) alone, or in combination with other conventional co-dispersants.
• Semi-crystalline PVOH which may preferably be employed in the present invention may have a viscosity DIN 53015 (Viscometry - Measurement of viscosity by means of the rolling ball viscometer by Hoeppler) ranging from 2 ⁇ 0.5 mPa-s to 18 ⁇ 0.5 mPa-s (4% aqueous solution at 20 °C) or more, a degree of hydrolysis (saponification) of 87.7 ⁇ 1 .0 mol.
• an ester value DIN 53401 (Determination of saponification value) of 140 ⁇ 10 mg KOH/g, a residual acetyl content of 10.8 ⁇ 0.8 w/w%, and a maximum ash content of 0.5% (calculated as Na 2 0), such as POVAL PVA 205, which is commercially available from Kuraray Europe GmbH, produced at Singapore; and MOWIOLTM 4-88, MOWIOLTM 18-88 and MOWIOLTM 23-88 G2 poly(vinylalcohol)s from Kuraray Europe GmbH, Division PVA/PVB Frankfurt am Main, Germany.
• MOWIOLTM 4-88 partially hydrolyzed PVOH (polyvinylalcohol) in granular form has a viscosity DIN 53015 of 4 ⁇ 0.5 mPa-s (4% aqueous solution at 20 ), a degree of hydrolysis (saponification) of 87.7 ⁇ 1 .0 mol. %, an ester value DIN 53401 of 140 ⁇ 10 mg KOH/g, a residual acetyl content of 10.8 ⁇ 0.8 w/w%, and a maximum ash content of 0.5% (calculated as Na 2 0).
• MOWIOLTM 18-88 partially hydrolyzed PVOH poly(vinylalcohol) in granular form, has a viscosity DIN 53015 of 18 ⁇ 2 mPa-s (4% aqueous solution at 20 ), a degree of hydrolysis (saponification) of 87.7 ⁇ 1 .0 mol. %.
• MOWIOLTM 23-88 G2 partially hydrolyzed PVOH (polyvinylalcohol) is in fine powder form, having a viscosity DIN 53015 of 23 ⁇ 1 .5 mPa-s (4% aqueous solution at 20 ), a degree of hydrolysis (saponification) of 87.7 ⁇ 1 .2 mol. %.
• PovalTM PVA 205 partially hydrolyzed PVOH (polyvinylalcohol) is in fine granular form, having a viscosity JIS K6726 of 5.0 ⁇ 0.4 mPa-s (4% aqueous solution at 20 ), a degree of hydrolysis (saponification) of 87.7 ⁇ 1 .0 mol. %.
• the dispersant, semi-crystalline polyvinyl alcohol may be employed in an amount such that the solid content of the semi-crystalline polyvinyl alcohol is at least 2.5% by weight, preferably from 5% by weight to 15% by weight, more preferably from 7.5% by weight to 10% by weight, based upon the total weight of the epoxy resin.
• the Mw of the semi-crystalline PVOH is from 5 to 400 kg/mol, more preferably, it is from 10 to 200 kg/mol, and most preferably, it is from 20 to 150 kg/mol.
• the PVOH molecular weight means the mean weight of the molar masses, Mw, determined by gel permeation chromatography (GPC) combined with static light scattering (absolute method) on re- acetylized specimens.
• the average particle size of the semi-crystalline PVOH is from 0.1 to 5 mm, more preferably, it is from 0.2 to 2 mm, and most preferably, it is from 0.1 to 1 mm.
• the hydrolysis degree of the semi-crystalline PVOH is between 50-99%, more preferably between 60-95%, and most preferably between 80-90%.
• the co-dispersant suitable for the present invention should maintain its efficiency at relatively high temperature (e.g. at 80-150 °C, preferably from 90 to 130 °C) when preparing the epoxy dispersion.
• An example of a class of the suitable co-dispersant is a sulfate of an ethoxylated phenol represented by the formula:
• ⁇ is acromatic group substituted phenol, preferably Di- and Tristyrenated phenol
• n is from 10 to 40, preferably from 14 to 20
• Z is sodium, potassium, or ammonium, preferably ammonium.
• Tristyrenated Phenol ammonium sulfate E-SPERSE 701 , a PEO (20) Di- and Tristyrenated Phenol sodium sulfate commercially available from Ethox Chemicals LLC.
• a class of the suitable co-dispersant is a nonionic dispersant characterized by having a molecular weight of greater than 7,000 and not more than 20,000.
• this high temperature nonionic dispersant has the following structure:
• each f is not less than 20, preferably not less than 40, and not greater than 1 00, preferably not greater than 80; and e is not less than 80, more preferably not less than 90; and preferably not greater than 400, more preferably not greater than 200, and most preferably not greater than 150.
• R is an epoxide functional group or hydrogen.
• Examples of commercially available high temperature nonionic dispersants include ATSURF 1 08 dispersant (Imperial Chemical Industries PLC (ICI)),
• the co-dispersant is used in an amount of from 0.1 to 10%, preferably from 0.1 to 4% by weight based on the total weight of the epoxy resins.
• Epoxy Dispersions 1 , and 3 to 5 were prepared utilizing a KWP (Krupp Werner & Pfleiderer) ZSK25 extruder (25 mm screw diameter, 60 L/D rotating at 450 rpm) according to the following procedure with the formulation components for each aqueous dispersion being reported in Tables 1 to 4 below.
• the solid epoxy resin and the semi-crystalline PVOH polymer were supplied to the feed throat of the extruder via a Schenck Mechatron loss-in-weight feeder and then melted blended, and then emulsified in the presence of initial aqueous stream.
• a liquid epoxy resin stream was injected into the melt zone to blend with the solid epoxy resin and semi-crystalline PVOH before emulsification.
• the emulsion phase was then conveyed forward to the dilution and cooling zone of the extruder where additional dilution water was added to form the aqueous dispersions having solid level contents in the range of from less than 70 weight percent.
• the initial aqueous stream, and the dilution water were all supplied by Isco dual syringe pumps (500 ml).
• the barrel temperature of the extruder was set to 1 10 °C. After the dispersion exited the extruder, it was further cooled and filtered via a 200 ⁇ mesh size bag filter.
• the Comparative Epoxy Dispersion 2 using a PVOH solution as dispersant was prepared utilizing a Bersdorff extruder (25 mm screw diameter, 36 L/D rotating at 450 rpm).
• D.E.R.TM 664U epoxy was fed by a loss-in-weight feeder.
• the melt zone of the extruder was maintained at 75 °C below the softening temperature of the epoxy resin (100 °C) to prevent epoxy resin flakes from caking at the bottom of the feed throat and the melt seal from rupturing.
• the MOWIOL 488 solution (27 wt% solid) was delivered by a pair of 500 ml_ Isco syringe pumps.
• the PVOH solution was too viscous to load by suction, and was poured into the empty Isco tubes, using a 0.5 inch diameter transfer line between the pump and the extruder to prevent high pressure from building up.
• a melt zone temperature of 75 °C, an emulsification zone of 1 10 °C and a dilution zone of 1 10 °C was employed to produce the smallest amount of undispersed epoxy.
• Solid epoxy resin feed rate 1 00 g/min.
• the epoxy dispersion was prepared on the Berstorff extruder and a 27% MowiolTM 488 dispersant in solution
• the initial aqueous stream (IA) is adjusted to minimize the particle size. Feeding semi- crystalline PVOH directly as dispersant enables us to achieve smaller epoxy particle size by adding less water in the HIPE zone, compared with the epoxy dispersion prepared with using PVOH solution.
• Example 2 Effect of powder size of PVOH on epoxy particle size in dispersion Several epoxy resin dispersions were prepared and summarized in Table 2. Minimum particle sizes and corresponding solid content in HIPE are listed in the table. POVALTM PVA 205 is a fine granular grade of PVOH, very similar to MowiolTM 488 in terms of chemistry. A smaller particle size of 0.43 ⁇ was achieved
• POVALTM PVA 205 is more efficient than MowiolTM 488.
• as low as 7% POVALTM PVA 205 can be used to prepare epoxy dispersion.
• Solid epoxy resin feed rate 1 00 g/min.
• semi-crystalline PVOH was fed at 1 0.0 g/min for dispersions 3 to 5 and 7.5 g/min for dispersion 6.
• IA feed rate can be calculated by [FeedRate(epoxy)+FeedRate(PVOH)]/(solid% in HI PE) -
• the IA in HIPE phase required to achieve minimum particle size is also dependent on the molecular weight of PVOH, in other words, high molecular weight PVOH as a dispersant required more water in the emulsification zone.
• fine powder grade PVOH MOWIOLTM 2388G2
• Solid epoxy resin feed rate 1 00 g/min and semi-crystalline PVOH was fed at 10.0 g/min.
• IA feed rate is 27.5 g/min
• Epoxy blend dispersions were also prepared by the extruder-based dispersion process. As described in the process, liquid epoxy was injected into the extruder to melt blend with solid epoxy and semi-crystalline MowiolTM 488 in situ and then emulsified.
• Dispersion 9 in Table 4 is an epoxy blend dispersion, with composition listed below.
• DER 667E/DER 331 (75/25) means the weight ratio of two resins is 75 to 25.
• a co-dispersant can be used in the dispersion process (dispersant 10).
• Solid epoxy resin feed rate 1 00 g/min. and semi-crystalline PVOH was fed at 1 0.0 g/min. IA feed rate is 27.5 g/min.

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